Two-stage engine starter control



Oct.'28, 1941. M. H. ELKIN 2,260,742

TWO-STAGE ENGINE STARTER CONTROL Filed May 15, 1940 lllllillllllllllll|l|li--,Q

INVENTOR.

whines/s: I BY ATTORNEY.

Patented Oct. 28, 1941 I 2,260,742 'rwo-smca ENGINE s'mn'mn common Manuel H. Elkin, Elmira Heights, N. Y., asaignor to Bendix Aviation Corporation, South Bend, Ind.,- a corporation or Delaware Application May 15, 1940, Serial No. 335,378

8 Claims.

The present invention relates to a two-stage engine starter control and morepartlcularly to adevice for initially energizing a starting system with reduced power to secure engagement of the gearing, and for causing full energization of the starting system after the gearing is completely engaged.

In starting systems which are used for cranking heavy duty power plants such as Diesel engines, it is customa ry to use quite powerful starting motors energized by batteries of comparatively high voltage. If gearing of the automatically engaging type is employed and the full voltage of the battery is initially appliedto the starting motor, the acceleration of the armature thereof is so energetic that a large amount of kinetic energy is built up in the rotating parts during the engaging movement of the pinion, so that a yielding connection of large torque capacity is necessary to properly cushion the engagement of the pinion and the initiation of the cranking operation. Since such cushioning devices are comparatively expensive, it is customary to energize the starting motor with a reduced voltage to secure engagement of the starter gearing, the application of the full voltage of the battery being delayed until after the gearing is fully engaged.

It is an object of the present invention to provide a novel two-stage starter control which is reliable and efficient in operation while being simple and economical in construction.

it is another object to provide such a device which is not critical of. adjustment nor liable to get out of adjustment due to variable operating conditions of the starter.

it is another object to provide such a device which is arranged to maintain energization of the starting motor without interruption irrespective of the functional condition. of the engine.

It is another object to provide such a device which interposes only such time delay of, the full energization of the starting motor as is necessary to proper operation of the starter.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing which illustrates semi-diagrammatically a starting system incorporating a preferred embodimerit of the present invention.

In the drawing there is illustrated a starting system including a source of electrical energy such as a battery I which is grounded at 2 and connected by a lead 3 to a starting switch 4 oi the starting switch 4 to a resistor 6 which in turn is connected by a "lead I to a starting motor I which is grounded at 8 to complete the starting circuit.

The starting motor 8 is provided with an extended armature shaft' II on which is mounted a starter drive, l2 0! conventional character which- .includes a pinion l3 adapted to be moved by acceleration of the motor shaft into engagement with a member such as a flywheel gear ll of an engine to be started.

The resistor 6 is of such value as to suitably reduce the voltage initially applied to the starting motor, and means are provided in the form of a bridging switch It for short-circuiting said resistance and applying the full battery voltage to the starting motor after engagement of the gearing. Means for closing the bridging switch i5 is illustrated in the form of an electromagnet I8 connected by a lead IT to the starting circuit lead 5, and through a lead I8, a holding resistance l9 and a lead 2| to the ground at 22. The holding resistance I9 is of such value as to reduce the current flow through the elcctromagnet Hi to a value merely suilicient to hold the switch i5 closed, but, insufiicient to cause closure thereof.

Means for short circuiting the resistance is to effect closure of the bridging switch i5 is provided in the form of a movable contact 23 connected by a lead 24 to the control circuit lead it and a stationary contact 25 connected to the control circuit lead 2|. Means for closing contacts 23, 25 is provided in the form of a coil 25 connected by leads 2'! and 28 to the starting circuit leads 5 and! respectively whereby said coil is bridged across the resistor 6 and is accordingly energized by the voltage drop across said resistor.

in the operation of this device, closure of the starting switch completes the starting circuit through the resistor 5 whereby the starting motor is energized at reduced voltage to secure engagement oi the starting pinion iii with the ensine gear til. at the same time, the electromagnet l6 oi the bridging switch it is energized by current passing through the resistance r it, but such energization is insuilicient to cause closure of said switch. Coil 25 is also at this time energized by virtue of its parallel relation with the resistor 6, but as long as the starting motor is free to revolve, the counter E. M. F. generated by such rotation prevents the voltage drop across the resistor 6 from assuming a value suiiicient to cause the coil 26 to close contacts any suitable character. A conductor. 5 connects 23, 25. 1

' defined in the claims appended When the starting pinion I3 is fully meshed with-the engine gear, further rotation of the starting motor is prevented by the resistance to rotationof the engine gear. ,Ihis stalling of the starting motor reduces its counter E. M. F. to zero, whereupon the voltage drop across the resistor 6 rises to a maximum value which is suificient to energize the coil 26 to close contacts 23, 25. Closure of these contacts causes full energization of electromagnet l whereby the bridging switch i5 is closed, short-circuiting the re- 4 by the operator permits the parts to return to their idle positions as illustrated.

It will be seen that there is here provided a I device which positively prevents application of the full battery voltage to the starting motor until full engagement of the gearing is efiected, while introducing no unnecessary time delay since the full voltage is applied to the motor immediately upon the stalling thereof caused by completion of the engagement of the starter gearing.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as hereto.

What is claimed is:

1. In a starting system for internal combustion engines, a source of electrical energy, a starting motor, a circuit connecting the same including a switch and a starting resistor, and means for short-circuiting the resistor including a magnetic switch, a control circuit for the magnetic switch including a holding resistance and a pair of bridging contacts in parallel therewith, and 1 means responsive to a predetermined voltage drop across the starting resistor to close said contacts.

2. In a starting system for internal combustion engines, a source of electrical energy, a starting motor, a circuit connecting the same including a switch and a starting resistor, and means for short-circuiting the resistor including'a magnetic switch, a control circuit for the magnetic switch including a holding resistance and a pair of bridging contacts in parallel therewith, and an electromagnet connected in shunt with the starting resistor operative to close said contacts responsive to a predetermined energization thereof.

3. A starting system for internal combustion engines including a source of electrical energy, a starting motor, a resistor and a starting switch, a bridging switch in parallel with the resistor, means including an electromagnet energized by closure of the starting switch to hold the bridging switch closed, and means including an electromagnet responsive to a predetermined voltage drop across the resistor for closing the bridging switch.

4. A starting system for internal combustion engines including a source of electrical energy, a starting motor, a resistor and a starting switch, a bridging switch in parallel with the resistor, electromagnetic means actuated by stalling oi the starting motor for closing the bridging switch, and manually'controllable means for energizing the closing means sufliciently to hold the bridging switch closed.

5. In a starting circuit for internal combustion engines, a battery, a starting motor, a resistor for reducing the flow of current from the battery to the starting motor, and a starting switch for completing said circuit, an electromagnetic switch for bridging the resistor including a coil in circuit with said battery and starting switch, a resistance in series with the coil for reducing the flow of current therein to a holding value, and means responsive to stalling of the starting motor for short-circuiting said holding resistance.

6. In combination with a starting circuit for internal combustion engines including a battery,

a starting motor, a resistor for reducing the flow of current from the battery to the starting motor, and a starting switch for completing said circuit, an electromagnetic switch for bridging the resistor, a control circuit for the bridging switch including a pair of contacts, and an electromagnet having a coil energized by the voltage drop across the resistor to close the contacts responsive to stalling of the starting motor.

7. In a two-stagestarter control for internal combustion engines, a starting system including a manual switch and a starting resistor, an electromagnetic switch in parallel with the resistor, a control circuit for the magnetic switch including a resistance arranged to reduce the current in the control circuit to a holding value for the magnetic switch, a pair of normally open contacts connected in shunt with the holding resistance, and means for closing said contacts in response to stalling of the starting motor.

8. A two-stage starter control as set forth in claim 7 in which the means for closing the contacts includes a solenoid connected in shunt with the starting resistor.

MANUEL H. ELKIN. 

